Subaru (R160 diff) Rear Locker project

Well I should probably post up here about the Locker project im working on. Many of you know how painful it is to have open or useless viscous lsd's in our Subaru's. 90% of Subarus from the mid 80's onwards use the R160 diff.
Now I didnt really want to pay a few thousand dollars for Cusco or some other for form of LSD. But the downside is that they are only LSD's not even lockers for that price.

I got the idea from Blue Fox who was working with using the rear drum brakes to create seperate leavers for each side and lock the one with the least traction to make the other wheel get the power needed to move the vehicle. From this I had the idea of just creating a locker, whether it be air, electronic or a leaver.
I have good skills at using CAD programs to design objects and buildings. So I am going to try and use my skills along with the help of others to come up with a locker for the R160 differential. I am not a fan of auto/E lockers and I have read that in manual transmission vehicles they jump, bounce and skit around on the roads abit. So if this project comes together it wont be an auto locker.

Another solution is to upgradeto R180 diffs then get a locker for that, but personally I dont want to have to go and change all my diffs around and mess with my gearing. I want to use what I have...

Our vehicles at stock are quite capable for a semi-offroader and with modifications are very capible. But there are moments that im sure most of you have gone 'if I had a locker I wouldnt of been stuck for hours' or "it would of made that hill so easy to climb', situations like that anyway.

Now for this project an engineer would be quite helpful but since one hasnt contacted me im kinda on my own for designing it. I have the support of many people over at AuSubaru and im sure I will here too.

I have acquired 2 R160 open 3.7 rear diffs that i will be picking up in Perth when I go in about 3 weeks time. Once I get them I can see actually how much room there is and start making measurements to come up with a design. I am probably going to have to design a new carrier then the locking mechanism.

Carl has offered to have a go at actually building it since he is a genius at making things out of blocks of steel :biggrin:

I am willing to get something out of this, even if its destroying a diff in the process. Now its not real hard after looking at other designs of lockers but it is going to take time. If anyone is willing to help, be supportive or has anything to comment post it here or give me a pm.

You can also check out the thread where I started it at Ausubaru.

https://www.ausubaru.com/forum/showthread.php?t=19545


Taza

This will be fun!!!

I do have a clue, but not much more, on how lockers work, so I'm going to have to educate myself a bit as well. I'll also hunt around and see if I can find myself an R160 diff. With proper gearing is the R160 adaptable to just about any of the Subaru models??? While I'm at it, I might just see if I can develop one for YotaRu as well.:ebiggrin:

Yes the R160 will fit in 90% of Subarus from the mid 80's onwards.

Three good places to educate yourself are Youtube, Google and Google images.

Once I get the two diffs I can see what little space there is as im told and the work with that.

taza said:

Yes the R160 will fit in 90% of Subarus from the mid 80's onwards.

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And its not limited to a set ratio either...

Cheers

Bennie

After some discussing over at Ausubaru I have found out that there was an auto locker created for the R160 diff about 15 years ago. It didn't sell to well and was canned. There were also a few problems that have been had with auto lockers and AWD vehicles. So I am 100% sure that what I come up with won't be an auto locker.
I also couldn't live with the clicking when cornering.

Taza

Yeah I've known about these for some time Taza. If the auto locker was able to be produced and not break itself, then I'm 100% sure that a manual locker can be produced for the r160.

Cheers

Bennie

I'm all for it, but I really do think that a true locking diff will break stuff. I've been talking with a good avid 4x4 buddy (Tony, the spotter in my rock crawling videos), and he has snapped stock axles on the Jeep Cherokee's when equipped with locking diffs, so it don't know. He is expressing concern with the CV Joint strength, U-Joint strength and overall diff straight to handle the load of a locker. In some instances where you need a locker, you can have the majority of the weight on the rear wheel that has traction, and asking it to push the vehicle up is a HUGE stress on the drivetrain and that axle. So I don't know, it could work, or it could be fragile, we'll just have to see I guess.

Like I said, I'm all for it. But a MUCH more inexpensive proof-of-concept to see if the Forester's could even handle a locking diff is to get a used one, weld it up, and test it out. If you snap an axle or break other parts, you'll have your answer.

Tony and I agree that independently operated handbrakes for each rear wheel will be best as it allows some slip so it's not exactly locked, just to give the drivetrain some slack/relief instead of absolute locked. Again, in theory anyway. I'll have my own proof of concept videos up here as soon as I can rip apart my center console to disconnect one of the rear brakes from the brake handle. Then we'll see. :biggrin:

That could be very true Josh but I know people have welded their diffs (in Subaru's) up before an not had an issue. But that does depend on what your planning on doing with your vehicle. For example with some of the things you do it could possibly break and if it did that wouldn't suprise me. But it could also work.
Plus with a manual locker you only have it locked when you want when comparing to a welded diff or auto locker.
I also had abit of a go at your brake idea, I disconnected my E-Brake and tried locking one side while I had diagnal spin. It moved the car slightly forward but not enough to get me through the situation. I still had most if not all of the the power at the rear axel going to the wheel with the least traction. But my rear drums may be stuffed, my hand brake doesnt work to well anyway. I usally just leave my car is gear when shes off so she doesnt roll away :lol:

Anyway we will see what happens.... But if it does work and doesnt brake too easily some of us are going to have mean little Subies

Taza

Personally I'd rather see a stronger silicon somehow put into the viscous center & rear diff bringing them up from a pissweak 4kg to around 15 - 20kg, much less than a locker but good enough for what we need & possibly a cheaper option.

taza said:

That could be very true Josh but I know people have welded their diffs (in Subaru's) up before an not had an issue. But that does depend on what your planning on doing with your vehicle. For example with some of the things you do it could possibly break and if it did that wouldn't suprise me. But it could also work.
Plus with a manual locker you only have it locked when you want when comparing to a welded diff or auto locker.
I also had abit of a go at your brake idea, I disconnected my E-Brake and tried locking one side while I had diagnal spin. It moved the car slightly forward but not enough to get me through the situation. I still had most if not all of the the power at the rear axel going to the wheel with the least traction. But my rear drums may be stuffed, my hand brake doesnt work to well anyway. I usally just leave my car is gear when shes off so she doesnt roll away :lol:

Anyway we will see what happens.... But if it does work and doesnt brake too easily some of us are going to have mean little Subies

Taza

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I'm not sure if you have rear discs or not, but on my XT, I have the disc brakes as part of the normal braking system, and inside the rotor, I have separate drums specifically for the e-brake. Since it's only used for e-brake and not for normal braking use, my e-brake still grips the car and doesn't let it move even when the lever is partially lifted. But we'll see how well it really does when I pull apart my console (hopefully tomorrow) and try it out. I'll even take a video of it.

I think the handbrake idea has merit in lifted wheel situations, but I don't think it will help you out when you have to climb that long, slippery slope where your diff. is going to want to switch power from one wheel to the next. That kind of situation is where your really going to want a lock.

As far as tearing up the drive train, this is why we have to make it and try it out before we can say it is a functional modification. I too have read about a few folks with welded diffs., seems like they just generally remove an axle for driving on pavement, works, but kind of a PITA.

At least for prototype and possibly even production, why not have the locker cable actuated??? Cheap, simple, and could follow the handbrake cable into the cabin.

carljwnc said:

At least for prototype and possibly even production, why not have the locker cable actuated??? Cheap, simple, and could follow the handbrake cable into the cabin.

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Thats the idea for the proto type.


Now someone might be able to inlighten me abit. Since the internet, email and phones were down at my work today (Im a computer tech), we couldnt do much so I had a long discussion for a couple of hours with a work colleague. He has a jeep wranger with a auto lcoker in the front, it works quite well for what it is, but then we got talking about AWD vehicles and lockers....
I know the torque is split 50/50 between the front and rear axels with a manual Subie and 60/40 or 90/10 with an auto depending on the year. Does anyone know if the centre diff is open, permantly locked or lsd? Because if I create a rear locker and the centre diff is lsd or open then little or no power will go to the rear wheels at all. Will I need to find a way to create a locking mechanism for the centre diff as well?

Can someone help shed some light on the issue for me?

Im pretty sure with an L-Series (and brumby) being a 4WD vehicle with FWD then Hi & Low range that when you engage 4WD it locks the centre diff. Am I right on that? They didnt have AWD to my knowledge so that wouldnt be an issue.

Cheers
Taza

I think you'll find the standard center diff is a 4kg viscous, as said earlier you can get 12kg, 20kg & I think there may be a rare 15kg but you are looking at $600ish for one of the stronger diffs 2nd hand, nice to be able to change the fluid if viscosity is the only difference & not being a locker you don't have the sudden jarring on the pissy little axles so less chance of snapping one out in the middle of nowhere.

taza said:

Can someone help shed some light on the issue for me?

Im pretty sure with an L-Series (and brumby) being a 4WD vehicle with FWD then Hi & Low range that when you engage 4WD it locks the centre diff. Am I right on that? They didnt have AWD to my knowledge so that wouldnt be an issue.

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The centre diff is a 4 or 5kg unit as d_generate has said. Apparently the 20kg unit is not a happy one for a daily driver - from what I've heard the 15kg unit is good for both daily driving and offroading.

As for the L series and MY's, they don't have a centre diff - just a mechanism that engages the rear drive to the drive that the front also receives...

Cheers

Bennie

What about creating a manual diff lock for the centre diff in AWD vehicles too? It wouldnt be too different from a rear or front diff. Could it? Then if you could lock 2 of the diffs you would have a decent chance offroad.

Thats also a good point Tom. So a 12kg would be the best for the centre and a front and rear locker. Its doable with time and money.


Taza

Yeah its a fair bit different!

I think we need to focus on one thing at a time!

Cheers

Bennie

El_Freddo said:

I think we need to focus on one thing at a time!

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Agreed, R160 rear diff locker project. Once it's done and tested we'll be able to tell if the center diff needs to be addressed.

I admire your enthusiasm for this Taza!

But as others have said: one thing at a time. I will watch with interest, and I'll let you know if I can do anything to help.

I want that locker so badly!! I´ll buy one, even if i get in financial trouble

SUBSCRIBED!!

carljwnc said:

Agreed, R160 rear diff locker project. Once it's done and tested we'll be able to tell if the center diff needs to be addressed.

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Ask anyone who rally's a WRX and they'll soon tell you which center diff you need.....12kg

But that's a simple solution so yeah concentrate on the rear. I still think axle snapping is going to be a problem so I think I'd rather have 3 decent LSD's, ATM I have one fairly good & two very ordinary ones but luckily the hard one is done.